Two piece pump rod

ABSTRACT

A metering pump includes a motor having a motor shaft extending through a drive housing, a carriage assembly disposed around the motor shaft and within the drive housing, a plunger return block mounted to the carriage assembly, a piston disposed along an axis, a carriage bearing disposed on the motor shaft and within the carriage assembly and slidably coupled to the carriage assembly, a cam coupled to the motor shaft to rotate with the motor shaft, and a bearing disposed around the cam to rotate therewith and to contact the stroke adjuster and the plunger return block. The piston also includes a stroke adjuster mounted to the carriage assembly, a plunger having a button-shaped protrusion end, and a drive shaft having a first end connected to the stroke adjuster and a second end having a hook protrusion configured to receive and engage the plunger button-shaped protrusion end.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of U.S. application Ser. No. 15/142,820filed Apr. 29, 2016 and entitled “TWO PIECE PUMP ROD,” which claimspriority to U.S. Provisional Application No. 62/155,577 filed on May 1,2015 and entitled “TWO PIECE PUMP ROD,” the entire contents of which arehereby incorporated by reference in their entireties.

BACKGROUND

Companies in the oil and natural gas industry often use metering pumpsto transfer fluids in harsh or remote locations. Many such pumps provideprecise fluid dispensation by converting rotational motion deliveredfrom a solar or AC grid powered motor to linear reciprocating motion ina piston. During a complete piston stroke, fluid is both drawn into thepump and discharged from the pump at a particular rate depending onpiston displacement and rotation cycle time. Frictional forces and sideloading acting within these pumps can cause both wear on pump componentsand operational inefficiency. Wear often decreases the life of thesecomponents and results in failure modes requiring downtime for repair.Pump inefficiency can increase demand load on the sources powering thepump. Minimizing component wear and pump inefficiency can thus reduceend-user costs.

While metering pumps typically drive a piston using a cam, many useeither spring or carriage assemblies to return the piston. In springassemblies, the spring force used to return the piston can act againstit during the discharge stroke, causing higher energy penalties andadditional wear on the pump head and rotary components. Carriageassemblies, by contrast, can require a number of additional parts tofacilitate piston return. Using additional parts often provides morewear points and thus more potential failure modes.

Metering pump pistons generally reciprocate within a channel. Frictionbetween the piston and the rotary components attached to the motor canimpart a slight rotation on the piston. This rotation in turn causesside loading on the parts forming the piston channel. Side loading onthese parts decreases the life thereof and can necessitate pump repair.It can also force end-users to purchase more replacement parts.

SUMMARY

In one embodiment, a metering pump includes a motor having a motor shaftextending through a drive housing, a carriage assembly disposed aroundthe motor shaft and within the drive housing, a plunger return blockmounted to the carriage assembly, a piston disposed along an axis, acarriage bearing disposed on the motor shaft and within the carriageassembly and slidably coupled to the carriage assembly, a cam coupled tothe motor shaft to rotate with the motor shaft, and a bearing disposedaround the cam to rotate therewith and to contact the stroke adjusterand the plunger return block. The piston also includes a stroke adjustermounted to the carriage assembly, a plunger having a button-shapedprotrusion end, and a drive shaft having a first end connected to thestroke adjuster and a second end having a hook protrusion configured toreceive and engage the plunger button-shaped protrusion end.

In another embodiment, a method of servicing a metering pump isprovided, wherein the metering pump includes a drive housing, a driveshaft, a drive cylinder, a dust cover disposed around the drivecylinder, a pump section that includes a packing nut, a fluid cylinder,and a plunger, and set screws that fasten the drive cylinder to thefluid cylinder. The method includes rotating the dust cover with respectto the drive cylinder, sliding the dust cover toward the drive housingto expose the packing nut, loosening the packing nut, removing the setscrews from the drive cylinder, releasing the drive cylinder from thefluid cylinder, disengaging the plunger having a button shaped end fromthe drive shaft having a hook shaped receiving end, and removing thepump section from the metering pump.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric view of a metering pump assembly.

FIG. 2A is an exploded isometric view one implementation of a meteringpump.

FIG. 2B is an isometric view of the metering pump shown in FIG. 2A.

FIG. 2C is a front view of the metering pump shown in FIG. 2A.

FIG. 2D is a top plan view of the metering pump shown in FIG. 2A.

FIG. 2E is a bottom plan view of the metering pump shown in FIG. 2A.

FIG. 3A is an isometric cross-sectional view of another implementationof a metering pump.

FIG. 3B is a front cross-sectional view of the metering pump shown inFIG. 3A.

FIG. 3C is a bottom plan cross-sectional view of the metering pump shownin FIG. 3A.

FIG. 3D is an enlarged view of metering pump 10 shown in FIG. 3C.

FIG. 4A is an enlarged isometric view of yet another implementation of ametering pump.

FIG. 4B is an enlarged front view of the metering pump shown in FIG. 4A.

DETAILED DESCRIPTION

FIG. 1 is an isometric view of metering pump assembly 2, which includestank 4 (which further comprises tank recirculation port 4R and tankmanifold assembly 4M), power source 6, pressure relief valve 8, meteringpump 10, and supply line L. Tank 4 is connected to metering pump 10.Metering pump 10 is connected to tank 4, power source 6, and pressurerelief valve 8. Pressure relief valve 8 is positioned downstream fromthe outlet of metering pump 10. Power source 6 provides electrical powerto metering pump 10. Metering pump 10 draws fluid from tank manifoldassembly 4M and then provides the fluid through supply line L to adesired location. Pressure relief valve 8 receives fluid from meteringpump 10 and can redirect fluid if the pressure surpasses a threshold.Fluid diverted by pressure relief valve 8 can be recirculated to tank 4through tank recirculation port 4R.

FIG. 2A is an exploded isometric view of one implementation of meteringpump 10. FIG. 2B is an isometric view of metering pump 10 shown in FIG.2A. FIG. 2C is a front view of metering pump 10 shown in FIG. 2A. FIG.2D is a top plan view of metering pump 10 shown in FIG. 2A. FIG. 2E is abottom plan view of metering pump 10 shown in FIG. 2A. FIGS. 2A-2E willbe discussed together in the following description. Metering pump 10includes motor section 12, drive housing section 14, pump section 16,and base section 18. Motor section 12 includes conduit 20 and motor 22.Motor 22 further includes junction box 24, motor housing 26, and motorshaft 28. Drive housing section 14 includes drive housing 30 (havingfirst drive housing port 30A and second drive housing port 30B), driveguard 32, carriage bearing 34 (which includes carriage bearing groove34G), carriage assembly 36 (which includes carriage assembly inner ridge36R), cam 38, ball bearing 40, plunger return block 42, stroke adjuster44, drive shaft 46 (which includes drive shaft receiving end 46R),stroke adjuster nut 48, sleeve bearing 50, drive cylinder matingcomponent 52, drive cylinder 54, set screws 56, and dust cover 58. Pumpsection 16 includes plunger 60 (which includes plunger button end 60B),packing nut 62, backup ring 64, o-ring 66, first plunger bearing 68,first spacer 70, second plunger bearing 72, packing seal 74, secondspacer 76, fluid cylinder 78, o-ring 80, valve housing 82, inlet checkvalve 84, and outlet check valve 86. Base section 18 includes base 90and base mounting surface 92.

Motor section 12 is connected to drive housing section 14. Drive housingsection 14 is connected to motor section 12, pump section 16, and basesection 18. Pump section 16 is connected to drive section 14. Basesection 18 is connected to drive housing section 14. Motor section 12provides rotational motion to the components in the drive housingsection 14. Drive housing section 14 converts rotational motion frommotor section 12 into a linear reciprocating motion to drive pumpsection 16. Pump section 16 provides fluid at a desired rate. Basesection 18 supports metering pump 10.

Regarding motor section 12, conduit 20 is connected to junction box 24of motor 22. Motor housing 26 is connected to drive housing 30. Motorshaft 28 is positioned to extend along a longitudinal axis of motor 22and into drive housing 30. Conduit 20 contains wiring that connects apower source to motor 22. Junction box 24 protects electrical componentsof motor 22 and connects to conduit 20. Motor housing 26 mounts motorsection 12 to drive housing 30 of drive housing section 14. Motor shaft28 extends and rotates through motor housing 26 into drive housing 30.Motor 22 imparts rotational motion via motor shaft 28 for conversioninto linear reciprocating motion in drive housing section 14.

Regarding drive housing section 14, drive housing 30 is connected tomotor housing 26, drive guard 32, carriage bearing 34, drive cylindermating component 52, drive cylinder 54, and mounting surface 92 of basesection 18. Carriage bearing 34 is connected to motor shaft 28, drivehousing 30, carriage assembly 36, and cam 38 and is positioned withincarriage assembly 36. Carriage assembly 36 is connected to plungerreturn block 42 and stroke adjuster 44 and is positioned around carriagebearing 34. Carriage assembly inner ridge 36R is positioned withincarriage bearing groove 34G. Cam 38 is connected to motor shaft 28 andis positioned to abut carriage bearing 34. Ball bearing 40 is connectedto and positioned to surround cam 38. Plunger return block 42 isconnected to carriage assembly 36. Stroke adjuster 44 is connected tocarriage assembly 36, drive shaft 46, and stroke adjuster nut 48. Driveshaft 46 is connected to stroke adjuster 44 and plunger 60 and ispositioned within sleeve bearing 50. Stroke adjuster nut 48 is connectedto stroke adjuster 44. The inner radial surface of sleeve bearing 50abuts drive shaft 46, while the outer radial surface of sleeve bearing50 abuts the inner radial surface of drive cylinder mating component 52.The inner radial surface of drive cylinder mating component 52 abuts theouter radial surface of sleeve bearing 50, while the outer radialsurface of drive cylinder mating component 52 abuts the inner radialsurface of drive housing 30 at first drive housing port 30A. Drivecylinder mating component 52 is also connected to drive cylinder 54.Drive cylinder 54 is connected to drive housing 30, drive cylindermating component 52, set screws 56, dust cover 58, packing nut 62, andfluid cylinder 78. Set screws 56 are connected to drive cylinder 54 andfluid cylinder 78 of pump section 16. Dust cover 58 is positioned aroundand is connected to drive cylinder 54.

Drive housing 30 protects internal components and mounts to motorsection 12, pump section 16, and base section 18. Drive housing 30 alsoconnects to drive guard 32. Drive guard 32 protects and allows access tocomponents within drive housing 30. Carriage bearing 34 mounts to motorshaft 28 and drive housing 30 and sits within carriage assembly 36.Carriage bearing 34 restricts the movement of carriage assembly 36 andalso provides a bearing surface upon which cam 38 can rotate. Carriagebearing 34 also acts as a second point of contact for carriage assembly36 in order to maintain horizontal alignment as carriage assembly 36reciprocates with the movement of stroke adjuster 44. Carriage assembly36 connects to stroke adjuster 44 and plunger return block 42 andfacilitates the return of drive shaft 46 and plunger 60 once depressedby cam 38 and ball bearing 40. Cam 38 connects to and rotates with motorshaft 28. Ball bearing 40 surrounds cam 38 and contacts stroke adjuster44 as cam 38 rotates, depressing drive shaft 46 and plunger 60. Plungerreturn block 42 provides a contact point for ball bearing 40 rotating oncam 38 to return the depressed piston formed in part by stroke adjuster44, drive shaft 46 and plunger 60. Stroke adjuster 44 serves as a firstcontact point for maintaining the horizontal alignment of carriageassembly 36 in conjunction with the second point of contact provided bycarriage bearing 34. Stroke adjuster 44 also depresses drive shaft 46and plunger 60 when contacted by ball bearing 40 and cam 38. Strokeadjuster 44 and stroke adjuster nut 48 allow for control of strokelength. Drive shaft 46 connects to and transfers linear motion toplunger 60. Sleeve bearing 50 supports and directs the motion of driveshaft 46. Drive cylinder mating component 52 fastens drive cylinder 54to drive housing 30. Set screws 56 secure drive cylinder 54 to fluidcylinder 78. Dust cover 58 provides a protective barrier over a portionof drive cylinder 54.

Regarding pump section 16, plunger 60 is connected to drive shaft 46,first plunger bearing 68, first spacer 70, second plunger bearing 72,packing seal 74, and second spacer 76. Plunger button end 60B isconnected to drive shaft receiving end 46R. Packing nut 62 is connectedto drive cylinder 54, backup ring 64, o-ring 66, first plunger bearing68, first spacer 70, second plunger bearing 72, packing seal 74, secondspacer 76, and fluid cylinder 78. First plunger bearing 68 is connectedto plunger 60, packing nut 62, and first spacer 70. The radial innersurface of first plunger bearing 68 abuts the radial outer surface ofplunger 60, while the radial outer surface of first plunger bearing 68abuts the radial inner surface of packing nut 62. First spacer 70 isconnected to plunger 60, packing nut 62, first plunger bearing 68, andsecond plunger bearing 72. The radial inner surface of first spacer 70abuts the radial outer surface of plunger 60, while the radial outersurface of first spacer 70 abuts the radial inner surface of packing nut62. Second plunger bearing 72 is connected to plunger 60, packing nut62, first spacer 70, and packing seal 74. The radial inner surface ofsecond plunger bearing 72 abuts the radial outer surface of plunger 60,while the radial outer surface of second plunger bearing 72 abuts theradial inner surface of packing nut 62. Packing seal 74 is connected toplunger 60, packing nut 62, second plunger bearing 72, and second spacer76. The radial inner surface of packing seal 74 abuts the radial outersurface of plunger 60, while the radial outer surface of packing seal 74abuts the radial inner surface of packing nut 62. Second spacer 76 isconnected to plunger 60, packing nut 62, packing seal 74, and fluidcylinder 78. The radial inner surface of second spacer 76 abuts theradial outer surface of plunger 60, while the radial outer surface ofsecond spacer 76 abuts the radial inner surface of packing nut 62. Fluidcylinder 78 is connected to drive cylinder 54, packing nut 62, secondspacer 76, and valve housing 82. O-ring 80 is connected to fluidcylinder 78. Valve housing 82 is connected to inlet check valve 84,outlet check valve 86, and bleed valve 88.

Plunger 60 connects to drive shaft 46 and moves in a linearreciprocating motion therewith. Plunger button end 60B connects to driveshaft receiving end 46R. As plunger 60 translates toward valve housing82, fluid is pushed through outlet check valve 86. As plunger is pulledaway from valve housing 82 and toward drive housing 30, fluid is drawninto valve housing 82 through inlet check valve 84. Packing nut 62,first plunger bearing 68, first spacer 70, second plunger bearing 72,packing seal 74, second spacer 76, and fluid cylinder 78 provide achannel within which plunger 60 reciprocates. Packing nut 62 pressesfirst plunger bearing 68, first spacer 70, second plunger bearing 72,packing seal 74, and second spacer 76 together to seal the channel.O-ring 66 and backup ring 64 provide a sealing interface between packingnut 62 and fluid cylinder 78. O-ring 80 provides a sealing interfacebetween fluid cylinder 78 and valve housing 82. Bleed valve 88 purgesair to facilitate proper fluid flow.

Regarding base section 18, base 90 includes a mounting surface 92.Mounting surface 92 is connected to drive housing 30. Base 90 mounts todrive housing 30 at mounting surface 92 and provides support formetering pump 10.

Metering pump 10 can draw fluid from tank manifold assembly 4M (shown inFIG. 1) into inlet check valve 84 and then discharge the fluid to supplyline L (shown in FIG. 1) through outlet check valve 86. Fluid is drawninto and discharged from metering pump 10 based on the displacement ofthe piston formed by stroke adjuster 44, drive shaft 46, and plunger 60and rotation cycle time of motor shaft 28, cam 38 and ball bearing 40.Metering pump 10 converts rotational motion from motor shaft 28, cam 38and ball bearing 40 into linear reciprocating motion in the piston.Plunger 60 and a portion of drive shaft 46 move linearly within achannel formed by sleeve bearing 50, drive cylinder mating component 52,packing nut 62, first plunger bearing 68, first spacer 70, secondplunger bearing 72, packing seal 74, second spacer 76, and fluidcylinder 78. A complete piston stroke includes both suction anddischarge strokes. The suction stroke draws fluid into inlet check valve84 to fill the volume formed by the face of plunger 60, packing nut 62,and valve housing 82. The discharge stroke pushes fluid out throughoutlet check valve 86 as the face of plunger 60 moves linearly in thedirection of valve housing 82 relative to drive housing 30.

Motor 22 rotates motor shaft 28, which in turn rotates cam 38 and ballbearing 40 in drive housing 30. The eccentric rotation of cam 38 andball bearing 40 acts to depress and return the piston so that itreciprocates within the channel formed by sleeve bearing 50, drivecylinder mating component 52, packing nut 62, first plunger bearing 68,first spacer 70, second plunger bearing 72, packing seal 74, secondspacer 76, and fluid cylinder 78. Carriage assembly 36 attaches toplunger return block 42 and stroke adjuster 44 and facilitates thesuction stroke of the piston. Carriage assembly 36, stroke adjuster 44,and plunger return block 42 act as a follower for cam 38 and ballbearing 40. The suction stroke of the piston begins when cam 38 and ballbearing 40 rotate to a position where the larger side of cam 38 isnearest to second drive housing port 30B, such that ball bearing 40pushes on plunger return block 42. Pressing plunger return block 42drives the carriage assembly 36 toward second drive housing port 30Balong an axis formed along the length of the piston and extendingthrough first drive housing port 30A and second drive housing port 30B.This in turn pulls plunger 60 away from valve housing 82 along the sameaxis, drawing fluid into inlet check valve 84 to fill the volume formedby the face of plunger 60, packing nut 62, and valve housing 82. As cam38 and ball bearing 40 continue to rotate into a position where thelarger portion of cam 38 is nearest drive housing port 30A, ball bearing40 pushes on stroke adjuster 44, depressing the piston formed by strokeadjuster 44, drive shaft 46, and plunger 60 and initiating the dischargestroke. Depressing the piston pushes both the piston and carriageassembly 36 toward first drive housing port 30A along the axis formedalong the piston and extending through first drive housing port 30A andsecond drive housing port 30B and dispenses the volume drawn in duringthe suction stroke through outlet check valve 86. The continued rotationof motor shaft 28, cam 38 and ball bearing 40 in turn drives thecontinued reciprocation of the piston.

Carriage bearing 34 confers the advantage of providing a second point ofcontact for maintaining the alignment of carriage assembly 36 along theaxis formed by first drive housing port 30A and second drive housingport 30B without needing any additional components or structures. Strokeadjuster 44 provides the first point of contact for carriage assembly 36in aligning carriage assembly 36 along the axis formed along the lengthof the piston and extending through first drive housing port 30A andsecond drive housing port 30B as it moves between first drive housingport 30A and second drive housing port 30B with the rotation of cam 38and ball bearing 40. Using carriage bearing 34 as the second point ofcontact for the alignment of carriage assembly 36 ensures that it doesrotate with respect to the axis formed along the length of the pistonand extending through first drive housing port 30A and second drivehousing port 30B. This also limits the rotation of the piston within thechannel. In prior art configurations, the use of additional bearings oreven a dummy piston is typically required to ensure that a carriageassembly will not rotate. Using additional parts provides more wearpoints and thus more potential failure modes. Carriage bearing 34, bycontrast, aligns carriage assembly 36 with the axis along the pistonwithout the need for additional parts, reducing possible failure modesand potential repair downtime.

The coupling and structure of drive shaft receiving end 46R and plungerbutton end 60B confer the advantage of minimizing the side load appliedto the channel components such as packing seal 74, ensuring a longeroperating life. The connection of drive shaft receiving end 46R andplunger button end 60B is positioned to ensure that it avoids enteringsleeve bearing 50 and packing seal 74 during the reciprocation of driveshaft 46 and plunger 60. In one implementation, plunger button end 60Bhas a button shape, while drive shaft receiving end has a correspondingshape, such as a hook, permitting the mating of the two ends. Thedriveshaft receiving end 46R and plunger button end 60B connectionprovides a degree of freedom of movement between drive shaft 46 andplunger 60 so that any flex or rotation imparted to drive shaft 46 isreduced or eliminated on plunger 60. As cam 38 and ball bearing 40rotate into contact with stroke adjuster 44, ball bearing 40 tends toprovide both a force depressing stroke adjuster 44 and drive shaft 46and an orthogonal force imparting a slight rotation to drive shaft 46.The orthogonal force is the result of drag friction between strokeadjuster 44 and ball bearing 40 as cam 38 rotates. Rotation of driveshaft 46 can impart a side load downstream on a portion of the channelmade up of packing nut 62, first plunger bearing 68, first spacer 70,second plunger bearing 72, packing seal 74, and second spacer 76. Thedegree of freedom in the connection mitigates or eliminates thepropagation of the rotation on drive shaft 46, reducing side loading tothe channel components. Reducing the side load on the channel componentsextends the operating life thereof. In particular, this connectionextends the life of packing seal 74 by reducing the potential sideloading applied from plunger 60 thereon. In addition, the drive shaftreceiving end 46R and plunger button end 60B connection also confers theadvantage of providing efficient changeover times, minimizing downtimefor repair.

In another embodiment of metering pump 10, a second piston and pumpsection, like the piston and pump section 16, can be added in place ofplunger return block 42. The second piston and second pump sectionoperate like the piston and pump section 16.

FIGS. 3A-3D illustrates another implementation of metering pump 10.FIGS. 3A-3D use similar reference characters to those used in FIGS.2A-2E, even though some of the components, such as motor housing 26 andcarriage assembly 36, differ somewhat in structure. A person of ordinaryskill in the pertinent art would recognize that components having thesame reference numerals perform the same or similar functions. FIG. 3Ais an isometric cross-sectional view of chemical metering pump 10. FIG.3B is a front cross-sectional view of metering pump 10 shown in FIG. 3A.FIG. 3C is a bottom plan cross-sectional view of metering pump 10 shownin FIG. 3A. FIG. 3D is an enlarged view of metering pump 10 shown inFIG. 3C. Metering pump 10 includes motor section 12, drive housingsection 14, and pump section 16. Motor section 12 includes motor 22,junction box 24, motor housing 26, and motor shaft 28. Drive housingsection 14 includes drive housing 30 (further comprising first drivehousing port 30A, second drive housing port 30B, drive housing upperportion 30U, and drive housing lower portion 30L), drive guard 32,carriage bearing 34 (which includes carriage bearing groove 34G),carriage assembly 36 (which includes carriage assembly inner ridge 36R),cam 38, ball bearing 40, plunger return block 42, stroke adjuster 44,drive shaft 46 (which includes drive shaft receiving end 46R), strokeadjuster nut 48, sleeve bearing 50, drive cylinder mating component 52,drive cylinder 54, set screws 56, and dust cover 58. Pump section 16includes plunger 60 (which includes plunger button end 60B), packing nut62, backup ring 64, o-ring 66, first plunger bearing 68, first spacer70, second plunger bearing 72, packing seal 74, second spacer 76, fluidcylinder 78, o-ring 80, valve housing 82, inlet check valve 84, andoutlet check valve 86. Also shown in FIGS. 3A-3D is axis A.

Motor housing 26 is connected to drive housing 30. Motor shaft 28 ispositioned to extend along a longitudinal axis of motor 22 and intodrive housing 30. Drive housing 30 is connected to motor housing 26,drive guard 32, carriage bearing 34, drive cylinder mating component 52,drive cylinder 54, and mounting surface 92 of base section 18. Carriagebearing 34 is connected to motor shaft 28, drive housing 30, carriageassembly 36, and cam 38. Carriage assembly 36 is connected to plungerreturn block 42 and stroke adjuster 44. Carriage assembly inner ridge36R is positioned within carriage bearing groove 34G. Cam 38 isconnected to motor shaft 28 and is positioned to abut carriage bearing34. Ball bearing 40 is connected to and positioned to surround cam 38.Plunger return block 42 is connected to carriage assembly 36. Strokeadjuster 44 is connected to carriage assembly 36, drive shaft 46, andstroke adjuster nut 48. Drive shaft 46 is connected to stroke adjuster44 and plunger 60 and is positioned within sleeve bearing 50. Strokeadjuster nut 48 is connected to stroke adjuster 44. The inner radialsurface of sleeve bearing 50 abuts drive shaft 46, while the outerradial surface of sleeve bearing 50 abuts the inner radial surface ofdrive cylinder mating component 52. The inner radial surface of drivecylinder mating component 52 abuts the outer radial surface of sleevebearing 50, while the outer radial surface of drive cylinder matingcomponent 52 abuts the inner radial surface of drive housing 30 at firstdrive housing port 30A. Drive cylinder mating component 52 is alsoconnected to drive cylinder 54. Drive cylinder 54 is connected to drivehousing 30, drive cylinder mating component 52, set screws 56, dustcover 58, packing nut 62, and fluid cylinder 78. Set screws 56 areconnected to drive cylinder 54 and fluid cylinder 78 of pump section 16.Dust cover 58 is positioned around and is connected to drive cylinder54.

Plunger 60 is connected to drive shaft 46, first plunger bearing 68,first spacer 70, second plunger bearing 72, packing seal 74, and secondspacer 76. Plunger button end 60B is connected to drive shaft receivingend 46R. Packing nut 62 is connected to drive cylinder 54, backup ring64, o-ring 66, first plunger bearing 68, first spacer 70, second plungerbearing 72, packing seal 74, second spacer 76, and fluid cylinder 78.First plunger bearing 68 is connected to plunger 60, packing nut 62, andfirst spacer 70. The radial inner surface of first plunger bearing 68abuts the radial outer surface of plunger 60, while the radial outersurface of first plunger bearing 68 abuts the radial inner surface ofpacking nut 62. First spacer 70 is connected to plunger 60, packing nut62, first plunger bearing 68, and second plunger bearing 72. The radialinner surface of first spacer 70 abuts the radial outer surface ofplunger 60, while the radial outer surface of first spacer 70 abuts theradial inner surface of packing nut 62. Second plunger bearing 72 isconnected to plunger 60, packing nut 62, first spacer 70, and packingseal 74. The radial inner surface of second plunger bearing 72 abuts theradial outer surface of plunger 60, while the radial outer surface ofsecond plunger bearing 72 abuts the radial inner surface of packing nut62. Packing seal 74 is connected to plunger 60, packing nut 62, secondplunger bearing 72, and second spacer 76. The radial inner surface ofpacking seal 74 abuts the radial outer surface of plunger 60, while theradial outer surface of packing seal 74 abuts the radial inner surfaceof packing nut 62. Second spacer 76 is connected to plunger 60, packingnut 62, packing seal 74, and fluid cylinder 78. The radial inner surfaceof second spacer 76 abuts the radial outer surface of plunger 60, whilethe radial outer surface of second spacer 76 abuts the radial innersurface of packing nut 62. Fluid cylinder 78 is connected to drivecylinder 54, packing nut 62, second spacer 76, and valve housing 82.O-ring 80 is connected to fluid cylinder 78. Valve housing 82 isconnected to inlet check valve 84, outlet check valve 86, and bleedvalve 88.

Cam 38 and ball bearing 40 rotate eccentrically with the rotation ofmotor shaft 28. Carriage assembly 36, stroke adjuster 44, and plungerreturn block 42 act as a follower for cam 38 and ball bearing 40. As cam38 and ball bearing 40 rotate in a circular path to a position where thelarger portion of cam 38 is nearest drive housing port 30A, ball bearing40 pushes on stroke adjuster 44, depressing the piston formed by strokeadjuster 44, drive shaft 46, and plunger 60. Depressing this piston inturn dispenses fluid through outlet check valve 86. As cam 38 and ballbearing 40 rotate to a position where the larger side of cam 38 isnearest to drive housing port 30B, ball bearing 40 pushes on plungerreturn block 42. Pressing plunger return block 42 drives the carriageassembly 36 and thus pulls piston formed by stroke adjuster 44, driveshaft 46, and plunger 60 back from the depressed position. Pulling backthis piston draws fluid through inlet check valve 84.

Carriage bearing 34 sits within carriage assembly 36 and reducesfriction for the reciprocating and linear translation of carriageassembly 36 between drive housing ports 30A and 30 B and along axis A.Carriage assembly inner ridge 36R couples to and translates alongcarriage bearing groove 34G. The coupling of carriage bearing 34 andcarriage assembly 36 at the carriage bearing groove 34G and carriageassembly ridge 36R interface restricts carriage assembly 36 fromtraveling in undesirable directions. In particular, the couplingprevents carriage assembly 36 from translating back and forth along theaxis extending through motor shaft 28 and drive guard 32 and up and downalong the axis extending through drive housing upper portion 30U anddrive housing lower portion 30L. It also prevents carriage assembly 36from tilting back and forth between drive guard 32 and where motorsection 12 mounts to drive housing 30.

Stroke adjuster 44 and carriage bearing 34 ensure the horizontalalignment of carriage assembly 36 with respect to axis A, as shown inFIG. 3B. Stroke adjuster 44 provides the first point of contact forcarriage assembly 36. Absent a second point of contact, carriageassembly 36 would be free to rotate around and with motor shaft 28 withrespect to axis A. Carriage bearing 34 provides a second point ofcontact to ensure that carriage assembly 36 maintains horizontalalignment. Using carriage bearing 34 as the second point of contactminimizes the number of components needed to align carriage assembly 36.Placing carriage bearing 34 on motor shaft 28 eliminates the need forincorporating additional aligning features, providing less wear pointsand possible failure modes. In prior art configurations, additionalcomponents, such as a dummy piston or multiple bearings, would berequired to align a carriage assembly as it reciprocated. Suchadditional components provide more wear points and failure modes, whichcan force end-users to purchase more replacement parts.

Drive shaft receiving end 46R connects to plunger button end 60B,minimizing the side load applied to plunger 60 channel components suchas packing seal 74. The connection is positioned to ensure that itavoids entering sleeve bearing 50 and packing seal 74 during thereciprocation of drive shaft 46 and plunger 60. As cam 38 and ballbearing 40 rotate into contact with stroke adjuster 44, ball bearing 40tends to provide both a force depressing stroke adjuster 44 and driveshaft 46 and an orthogonal force imparting a slight rotation to driveshaft 46. The orthogonal force is result of drag friction between strokeadjuster 44 and ball bearing 40 as cam 38 rotates. The rotation of driveshaft 46 in turn imparts side load on the channel components. Thedriveshaft receiving end 46R and plunger button end 60B connectionprovides a degree of freedom between drive shaft 46 and plunger 60 sothat any flex or rotation imparted to drive shaft 46 is reduced oreliminated on plunger 60, minimizing the side loading on first plungerbearing 68, first spacer 70, second plunger bearing 72, and packing seal74. Reducing the side load on packing seal 74 increases the lifethereof. In addition, the drive shaft receiving end 46R and plungerbutton end 60B connection permits efficient changeover.

FIG. 4A is an enlarged isometric view of yet another implementation ofmetering pump 10. FIG. 4B is an enlarged front view of metering pump 10shown in FIG. 4A. Drive housing section 14 includes drive housing 30,drive guard 32, drive shaft 46 (which includes drive shaft receiving end46R), drive cylinder mating component 52, drive cylinder 54, set screws56, and dust cover 58. Pump section 16 includes plunger 60 (whichincludes plunger button end 60B), packing nut 62, and fluid cylinder 78.Drive housing 30 is connected to drive guard 32, and drive cylindermating component 52. Drive shaft receiving end 46R of drive shaft 46 isconnected to plunger button end 60B of plunger 60. Drive cylinder matingcomponent 52 is connected to drive housing 30 and drive cylinder 54.Drive cylinder 54 is connected to fluid cylinder 78. Set screws 56 areconnected to drive cylinder 54 and fluid cylinder 78. Dust cover 58 isconnected to drive cylinder 54.

Plunger 60 can be serviced or replaced quickly without the use ofspecial tools and, in some instances, without removing drive guard 32.To disconnect plunger 60, packing nut 62 can be exposed by rotating dustcover 58 and sliding it back toward drive housing 30. Packing nut 62 canthen be loosened. Set screws 56 can then be loosened from drive cylinder54, which is fastened to fluid cylinder 78. Once set screws 56 have beenremoved, fluid cylinder 78 can be released from drive cylinder 54. Insome embodiments, drive guard 32 can be removed in order to repositioncam 38 (as shown in FIGS. 2A and 3A), such that the larger side of cam38 is aligned with the side being repaired. In other embodiments, cam 38may not need to be adjusted. Plunger 60 can then be disengaged fromdrive shaft 46 at the coupling of driveshaft receiving end 46R andplunger button end 60B. Decoupling plunger 60 and drive shaft 46 allowsfor pump section 16 to be removed without needing to access the insideof drive housing 30 or using a special tool to disengage plunger 60 fromdrive shaft 46. Plunger 60 can thus be quickly repaired, serviced, orreplaced to ensure that the downtime of metering pump 10 is minimized.

To reconnect a replacement plunger, the replacement plunger buttonshaped end can be connected to drive shaft receiving end 46R. Thereplacement plunger can then be guided into fluid cylinder 78, as fluidcylinder 78 is guided into drive cylinder 54. Set screws 56 can then beused to fasten drive cylinder 54 to fluid cylinder 78. Packing nut 62can then be tightened. Dust cover 58 can then be pushed forward awayfrom drive housing 30 and then rotated to lock into place. The couplingand structure of drive shaft receiving end 46R and plunger button end60B thus confer the advantage of providing easy and efficientchangeover, minimizing downtime for repair.

While the invention has been described with reference to an exemplaryembodiment(s), it will be understood by those skilled in the art thatvarious changes may be made and equivalents may be substituted forelements thereof without departing from the scope of the invention. Inaddition, many modifications may be made to adapt a particular situationor material to the teachings of the invention without departing from theessential scope thereof. Therefore, it is intended that the inventionnot be limited to the particular embodiment(s) disclosed, but that theinvention will include all embodiments falling within the scope of theappended claims.

The invention claimed is:
 1. A method of servicing a metering pump,wherein the metering pump includes a drive housing, a drive shaft, adrive cylinder, a cover disposed around the drive cylinder, a pumpsection that includes a packing nut, a fluid cylinder, and a plunger,and set screws that fasten the drive cylinder to the fluid cylinder, themethod comprising: moving the cover with respect to the drive cylinderto expose the packing nut; loosening the packing nut; removing the setscrews from the drive cylinder; releasing the fluid cylinder from thedrive cylinder; disengaging the plunger; and removing the pump sectionfrom the metering pump.
 2. The method of claim 1, wherein disengagingthe plunger includes disengaging a button shaped end of the plunger froma hook shaped receiving end of the drive shaft.
 3. The method of claim2, further comprising replacing the plunger in the pump section with areplacement plunger having a button shaped end.
 4. The method of claim3, further comprising connecting the replacement plunger to the hookshaped receiving end of the drive shaft.
 5. The method of claim 4,further comprising guiding the replacement plunger into the fluidcylinder.
 6. The method of claim 5, further comprising guiding the fluidcylinder into the drive cylinder.
 7. The method of claim 6, furthercomprising fastening the drive cylinder to the fluid cylinder using theset screws.
 8. The method of claim 7, further comprising tightening thepacking nut.
 9. The method of claim 8, further comprising adjusting thecover with respect to the drive cylinder.
 10. The method of claim 9,wherein adjusting the cover with respect to the drive cylinder includessliding the cover away from the drive housing and toward the fluidcylinder.
 11. The method of claim 9, wherein adjusting the cover withrespect to the drive cylinder includes rotating the cover to lock thecover in place.
 12. The method of claim 1, wherein moving the cover withrespect to the drive cylinder includes sliding the cover toward thedrive housing.
 13. The method of claim 1, wherein moving the cover withrespect to the drive cylinder includes rotating the cover.
 14. Themethod of claim 13, wherein rotating the cover includes locking thecover in place.
 15. The method of claim 1, further comprising replacingthe plunger in the pump section.
 16. The method of claim 1, furthercomprising servicing or repairing the plunger in the pump section. 17.The method of claim 1, wherein disengaging the plunger includesdisengaging the plunger from the drive shaft.
 18. The method of claim 1,further comprising repositioning a cam within the drive housing of themetering pump.
 19. The method of claim 18, further comprising removing adrive guard from the drive housing.
 20. The method of claim 1, whereinremoving the pump section from the metering pump includes keeping thecomponents inside of the drive housing in place.